Life History and Behavior

Behavior

Morphology: Worms are about 2-3cm long. The body is the worm is made up of four sections: head, thorax, abdomen, cauda. The head and thorax are usually in the flared end of the tube when the worm is undisturbed.

Tube Building Behavior: Sand particles are passed from the tentacles at the head, to the mouth and then to the building organ. In the building organ the grains are coated with the “cement” that the worm uses to build its tube. The coated sand grain is then put into place at the flared end of the tube.

Tube Dwelling Behavior: When feeding and undisturbed, the worm will extend its head and tentacles out of the tube. If is is threatened, it will contract its body and retract it into the tube. Even when the worm is retracted into the tube, it can increase water flow to the head by thoracic pumping. Worms are observed to have an 90 to 180 degree twist along the their bodies.

Movement in the Tube: When the worm is partially out of its tube, it moves up and down by a method referred to as paella walking.

Connection to the Tube: The worm is able to remain in the tube through the use of uncirigerous tori. These tori are placed so that water flow is still efficient throughout the tube.

Feeding Behavior: When the worm is actively feeding, ciliary currents are observed throughout the tube. These currents are due to transverse bands of cilia along the dorsal surface, as well as cilia long the lateral body.

Defecation: The worm is able to defecate by using peristaltic waves that move from the cauda to the abdomen. The fecal matter is passed to the posterior margin of the ventral plate where the feces is expelled from the tube.

"The sandcastle worm Phragmatopoma californica, a marine polychaete, constructs a tube-like shelter by cementing together sand grains using a glue secreted from the building organ in its thorax. The glue is a mixture of post-translationally modified proteins, notably the cement proteins Pc-1 and Pc-2 with the amino acid, 3,4-dihydroxyphenyl-L-alanine (DOPA). Significant amounts of a halogenated derivative of DOPA were isolated from the worm cement following partial acid hydrolysis and capture of catecholic amino acids by phenylboronate affinity chromatography. Analysis by tandem mass spectrometry and 1H NMR indicates the DOPA derivative to be 2-chloro-4, 5-dihydroxyphenyl-L-alanine. The potential roles of 2-chloro-DOPA in chemical defense and underwater adhesion are considered." (Sun et al. 2009:126)

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Sandcastle worms live in colonies, building tube reefs somewhat similar to sandcastles (hence the name), which are often seen on rocky beaches at medium and low tide. The sandcastles, which have a honeycomb-like outward appearance,can cover an area of up to 2 meters (6.6 ft) on a side.[3] They may share areas with mussel beds and are found in any place that provides some shelter, such as rock faces, overhanging ledges and concave shorelines.[4]

The worms remain in their tubes and are almost never seen. At low tide, when above the water, they close the entrance to their tubes with a shield-like operculum made of dark setae. When submerged, they extend their tentacles out of the tube to catch food particles and sand grains. The grains are sorted, with the best ones used to keep the tube in repair,[3] and the rest ejected. The colonies are formed by the gregarious settlement of larvae, which require contact with an existing colony to metamorphose into adult worms.[4]

Sandcastle worms should not be confused with the similar, but more northern Sabellaria cementarium which are found from Alaska to southern California and have an amber-colored operculum.[4]

In 2005, researchers from the University of California, Santa Barbara (UCSB) discovered that the glue used by the phragmatopoma to build its protecting tube was made of specific proteins with opposite charges. Those proteins are called polyphenolic proteins[5] that are used as bioadhesives.[6] They succeeded in obtaining the sequence of these adhesive proteins and described the detailed mechanisms by which the adhesive sets. Inspired by these results University of Utah researchers reported in 2009 that they succeeded in duplicating the glue that the worms secrete and use to stick sand grains together underwater. The typical amount of glue that the worm produces at once is approximately 100 picoliters, requiring 50 million to fill a teaspoon.[7]

They believe the glue to have applications as a biocompatible medical adhesive, for instance to repair shattered bones.[8] If found to be practicable, the synthetic glue, which is based on complex coacervates, could be used to fix small bone fragments, instead of metal stabilizer devices such as pins and screws, which are challenging to use.[8] Other potential medical applications include sealing skin cuts, repair of cranio-facial bones, and corneal incisions.[7]

Obstacles include ensuring that the bond is to the substrate rather than the surface layer of the water. Another is that in order to cure, glues need need to dry out. Most either do not cure underwater or set too quickly.[7]

The proteins that are the basis of its adhesive contain side chains of phosphate and amine groups, which are well-known adhesion promoters which probably helps wet the surface. The glue has two parts, with different proteins and side groups in each. The two are made separately in a gland, like an epoxy, and mix as they are secreted. The glue sets in about 30 seconds, probably triggered by the large difference in acidity between the acidic glue and seawater. Curing takes about six hours, as the proteins cross-link, reaching the consistency of shoeleather.[7]

Existing medical superglues are highly immunogenic. Initial experiments with the new synthetic on animals show no immune response. But inside the body, the glue needs to eventually degrade, ideally at roughly the same rate as the bone or tissue regrows. Degradable versions therefore include proteins that are broken down by specialized cells.[7]

^Hinton, Sam (1987). Seashore life of southern California: an introduction to the animal life of California beaches south of Santa Barbara. California natural history guides 26. University of California Press. p. 48. ISBN978-0-520-05924-5.